In the traditional art, it is known that a transfer press has been provided with a transfer feeder for carrying a workpiece into and out of a press system, or for sequentially conveying workpieces into successive working stations.
Conventionally, the transfer feeder for conveying the workpieces has been provided with a pair of transfer bars which are operable to move in two-dimensional or three-dimensional directions, the transfer feeder having been so constructed as to be driven by a cam rotated by the power that is taken out from the press system.
In the conventional transfer feeder employing the cam-drive system, however, the movement of the transfer bars is eventually determined by a profile of the cam. Accordingly, a problem has then arisen such that the movement pattern is not readily variable in accordance with the workpieces which are being conveyed. On the other hand, if the movement patterns of the transfer bars are made variable, a plurality of cams have been required in accordance with the movement patterns which are to be altered from one to another. This requirement has made the drive mechanism unduly complex and the entire system prohibitively expensive, and has involved various inconveniences including, among others, the restriction imposed on the number or the movement patterns that can variably be chosen by selecting the number of cams.